The invention relates to tree delimbing devices, specifically to attachments to the delimbing machines equipped with booms.
The felling and harvesting of timber is not an easy task, especially for larger trees. The timber industry is continually in search of better and faster methods to harvest and process felled trees. One necessary task in the harvesting of trees is the removal of rotten or useless pieces of the tree. This removal of useless pieces of the tree along with the discarding of parts of the trunk that have either become rotten or that are too small in diameter to be of use includes removing parts of the trunk that have a break or a snag. The above task is necessary given the conditions surrounding the growth and harvesting of trees. For the timber industry, the most useful, and therefore most important part, of the tree is the healthy trunk with a mostly uniform diameter. Thus, other parts of the tree, such as its branches, are not as important and can be discarded. Another part of the tree that can be discarded is its top. Given that trees grow out from the top most part of its crown, the top end of the trunk, the most recent growth of the tree, does not have a diameter similar to the rest of the trunk. As such, this top end of the trunk must be discarded to yield the useful parts of the trunk. Furthermore, since trees that are felled are not immediately processed and sent to a timber plant, felled trees can lie on the ground for significant periods of time. Unfortunately, this can result in rot setting at the bottom of the trunk. Such rotten ends of the trunk are also useless and must be discarded.
Another problem with rot arises when the felled tree has a break in the trunk. Such a break, because of being left on the ground for significant periods of time, can cause rot in both parts of the broken trunk. The two ends of the trunk would therefore have to be cleaned up by removing their rotten ends. This operation involves cutting the trunk close to the position of the break on the trunk. Often, this position is somewhere within the middle portion of the trunk where the tree can be at its thickest.
From the above, it can be seen that the processing of a tree trunk to remove the useless portions can have three distinct steps:
1) removal of the tree top or broken end (topping)
2) removal of the rotten end of the trunk (butting)
3) removal of the branches or limbs (delimbing)
This processing is ideally done at the tree harvesting site and before the tree trunk is sent to the timber plant. Numerous machines have therefore been invented to try and make the above process easier.
A patent issued to Jorgensen, Canadian patent 779,081, discloses a machine for the trimming of felled trees. The machine has a telescoping boom and a gripping tool at the end of the boom. The machine removes the limbs of a felled tree by moving the gripping tool down the trunk of the felled tree. The gripping tool is equipped with a trimming tool that can remove the less useful tree tops from the trunk. Also disclosed in the patent is a second device attached farther down the boom. This second device is a cutting tool of the saw or shears type capable of cutting the tree into specific lengths and removing rotten portions of the trunk.
Unfortunately, the above device suffers from a number of draw backs. Specifically, it suffers from having to move the felled tree up the boom to remove both rotten portions of the trunk and the tree top. To remove the tree top and rotten portion of the trunk while preserving the trunk""s length, the machine (1) picks up the tree for the first time from the tree top end, (2) removes the top, (3) removes the limbs, (4) drops the tree, (5) picks up the tree for a second time from its bottom end, then (6) removes the rotten end. This necessitates numerous steps that the machine operator has to follow along the with the attendant consumption of fuel and time. Also, the patent notes that if the trunk is gripped from its bottom end, the total working range of the machine is reduced.
Another device using a sliding boom mechanism is disclosed in U.S. Pat. No. 5,568,829 issued to Crawford et al. Crawford et al discloses a delimber machine with a grappling head having grappling arms and a topping saw. Unfortunately, this topping saw is only capable of removing the tops of trees. There is no means disclosed for removing rotten ends of large trunks.
It is clear from the above that an improved delimbing head is needed that does not suffer from the above drawbacks. What is required is a delimbing head that simplifies not only the delimbing operation but also the topping and butting operations as well. Such a head would combine all three operations into one device and can preferably be retrofitted onto existing boom-type delimbing machines.
The present invention overcomes the deficiencies identified in the prior art by providing a tree delimbing head which combines a topping knife assembly with a butting saw assembly in a single unit.
The present invention provides for a delimbing head for a tree delimbing apparatus having a boom, the head comprising a body, boom attachment means to attach the body to the boom, a chainsaw assembly attached to the body, a topping knife assembly attached to the body, and a gripping arms assembly attached to the body wherein
1) the gripping arms assembly grips a felled tree trunk such that a longitudinal axis of the trunk is substantially parallel to the boom and
2) the chainsaw assembly, the knife assembly, and the gripping arms assembly are disposed in a single line on the body of the head.
Preferably, the chainsaw assembly comprises a chainsaw pivotally attached to the body by a pivot attachment means, means to operate the chainsaw, and means to controllably swivel the chainsaw about the pivot attachment means, wherein a controllable swivel of the chainsaw defines a cutting plane and said cutting plane is substantially perpendicular to the boom.
More preferably, the gripping arms assembly includes at least one pair of cooperating arcuate gripping arms and means to operate the or each pair of gripping arms between an open position and a closed position.
Most preferably, the knife assembly includes a pair of cooperating blades defining a cutting jaw and means to operate the cutting jaw between an open jaw position and a closed jaw position wherein in the closed jaw position a plane defined by the cooperating blades is substantially perpendicular to the boom.
Conveniently, each gripping arm has a lip on an inner circumference, said lip having at least one cutting edge defining an arcuate plane, said arcuate plane being substantially parallel to the longitudinal axis of the trunk.
More conveniently, the gripping arms assembly is between the chainsaw assembly and the knife assembly.
Most conveniently, the chainsaw assembly further includes a saw assembly delimbing blade attached to a bottom part of the chainsaw assembly wherein a plane defined by a cutting edge of the saw assembly delimbing blade is substantially parallel to the boom.
Also preferably, the knife assembly further includes a knife assembly delimbing blade attached to a bottom part of the knife assembly wherein a plane defined by a cutting edge of the knife assembly delimbing blade is substantially parallel to the boom.
In another embodiment of the invention, there is provided a delimbing head for a tree delimbing machine having a boom, the head including means to slidably attach the head to the boom, means to control the position of the head on the boom, chainsaw cutting means pivotally attached to the head, trunk gripping means for gripping a tree trunk, said trunk gripping means being attached to said head, topping knife means attached to said head, and a plurality of delimbing blades attached to said head, each delimbing blade having a cutting edge defining a plane parallel to a longitudinal axis of the trunk.
Yet another embodiment of the invention provides for a delimbing head for a tree delimbing machine having a telescopic boom, the head including means to attach the head to the boom, a chainsaw pivotally attached to the head, a pair of arcuate pincers for gripping a tree trunk about a circumference of the trunk, the pincers having an open and a closed position and at least a pair of cutting edges parallel to a longitudinal axis of the trunk, a pair of cutting jaws for cutting tree tops, and delimbing blades attached to said head, each delimbing blade having a cutting edge defining a plane parallel to a longitudinal axis of the trunk wherein the chainsaw, the cutting jaws, and the arcuate pincers are adjacent to one another.
The advantages of the invention are numerous. The need for a butting saw close to the cab of a delimbing machine is removed, thus making the machine cheaper. By combining the butting saw with the topping knives, less movement of the boom is required. Also, any length of trunk can be cut off from the main tree trunk using the butting saw. Furthermore, the head can be retrofitted to existing delimbing machines, obviating the need to buy a completely new machine to take advantage of the benefits of the new head.